1. Technical Field
The present disclosure relates to a semiconductor device and a display device, and more particularly to an alignment mark of a semiconductor device connectable to a transparent substrate in a display device employing a Chip-on-Glass (COG) method.
2. Description of Related Art
In a display device employing a Chip-on-Glass (COG) method, which is a technique for directly mounting a driving IC (IC chip) on a transparent substrate without interposing an FPC (Flexible Printed Circuit) or similar designs, where electrode terminals provided on the transparent substrate are connected to the IC chip to drive the display device. The transparent substrate is provided with electrodes, such as pixel electrodes for driving the display device, and the electrode terminals for supplying signals from the IC chip to the electrodes. Pads of the IC chip are connected to the electrode terminals through protruding electrical contacts called solder balls hereinafter, and output the signals for driving the display device to the electrodes.
An alignment mark on the IC chip may be formed by etching one of layers of the IC chip to form a pattern. The pattern may consist of two contrasting shapes including a first shape that scatters incident light from the photodetector, and a second shape that efficiently reflects the incident light in an incident direction, such that the first shape appears dark and the second shape appears light. Accordingly, the second shape is used to align with the alignment mark on the transparent substrate.
However, because the first shape and the second shape are formed by the same layer, contrast between the bright region and the dark region of the alignment mark on the IC chip is apt to be low. Accordingly, it is difficult to detect the alignment mark on the IC chip with a photodetector or naked eyes, and therefore a highly accurate alignment may be difficult to obtain.
What is needed, therefore, is to provide an item which overcomes the above-mentioned problems.